Objective Widely pacemaker/implantable cardioverter defibrillator (ICD) implantation is also related to an increasing need for transvenous lead extraction.Understanding the location and extent of pathological changes,including adhesions and fibrous tissue formation along the course of chronic pacemaker/ICD leads,are essential for operators performing lead extraction operations in order to reduce the potential life threatening complications.Methods Three parts are included in the research,pathological examination on 83 extracted pacemaker/ICD leads using excimer laser technique from March 2008 to March 2011,autopsy examination of one died patient during lead extraction for lead-related infective endocarditis,and anatomical analysis on pacemaker/ICD leads from 10 patients died of other non-cardiac causes.Results Extensive encapsulated fibrous tissue around the leads and extensive adhesion/fibrosis along the course of the leads from venous entry site to the lead/myocardial interface could be detected on transvenous pacemaker/ICD leads.Since the tissue at the junction between superior vena cava (SVC) and right atrium (RA) is very thin,free of pericardium,thus,this is a common place for extensive adhesion/fibrosis and myocardial perforation/tear during lead extraction,which accounted for one death during extraction in our cohort.Extensive adhesion and fibrosis were also observed at the tricuspid valve and subvalvular structures.Leads implanted to the right ventricular apex were close to the epicardial surface and prone to perforation through myocardium.It is common to observe thrombus on the leads or at the interface between leads and myocardial tissue,especially at right atrial appendage (RAA) at the site of lead insertion.Conclusion Extensive adhesions and fibrosis can be commonly seen along the course of pacemaker/ICD leads,and at SVC to RA junction,the tricuspid valve/subvalvular structures,and RA/RV lead interface.The tissue at SVC to RA junction is very thin,making it vulnerable for myocardial perforation/tear during lead extraction.Thrombus is commonly seen along the leads or at the lead-tissue interface.